460 lpg conversion - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

ando · 08-11-2004, 04:58

hi everyone can anyone help me i have just bought a 460bb with stage 4 cam, double valve springs,standard valves,850 double pumper on a torker 2 manifold also has mallory electronic ignition. I want to convert it to straight lpg gas to put into my f100. The engine also came with a c6 with 2200 rpm stall converter. i have a c6 in my f100 now behind a 302 clevland on straight gas carby. What should i do to the engine??? also should i run twin gas carbys or run twin throttle body gas system?? Any help would be great full. I also got a us strange 9 inch diff centre with a 4.56 ratio but i think this would to high for my f100 i do a lot of freeway driving. Any help would be greatfull cheers shane. the engine and running gear came out of ford galaxie 72 model

gregaust · 08-12-2004, 02:08

Try a P.M to TONYK on this website..He has been through this with his 460 XD

tonyk · 08-12-2004, 05:29

Hi Ando...
Engine is probably a D3VE headed (low comp) motor. If you want to pull it apart a set of hyper pistons (flat top) will bring comp up to 10:1 which is good for LPG.
If the motor is good though leave it alone. They get expensive when you go inside them. I run a twin impco system with twin convertors also and large primary liquid line. This seems to cope OK with my setup.

What is a stage 4 cam? lift, duration etc?
torker 2 is good.
2200 rpm is about 400 higher than stock 11" convertor so no probs there.
4.56 is too high for such a big motor but your cam may be too big.
BBF's like to be loaded up. They are a work horse not a high rev thing.
I would think the 4.56 is there to make the F truck really jump off the line.
A good highway ratio is 3.5 or 3.25.

A friend has a 2.75 and it goes like a cut cat so its not as important unless you want a drag car. I run a 3.25 and am thinking of going to 3.7. I have a 3000rpm convertor.
the cam is a crane powermax 296H.

When you have gone to str8 gas put a twin 3" on it (in stainless for long life) and get oxygen sensor bungs welded in before the crossover. You can tune with a MOTEC then. Tuning the impco right is an art though.

Where are you located?

ando · 08-17-2004, 02:13

Thanks for the reply guys. The motor has 10.5: 1 compression already and has standard pistons in it. It has been port matched. How much did it cost for you to set up the twin system on your car? I already have a straight gas carb on the 302 so i should sell it and get the twin throttle body setup? Im at penrith NSW

TyreToaster · 08-19-2004, 03:56

if you have the impco 425 carbs single or twin you will never get it to run the correct mixtures. Especially with you having the larger cam probably 225/236 duration 530/560ish lift you will find it either lean as buggery up high or rich as buggery down low and becuse you motor will utilise the larger rev range you may not be happy with the end result.

If you want it to run right make good power and not melt your pistons try buying s/h gas research setup much better option than the single stage adjustable IMPCO.

P.S before all you impco owners start abusing me and telling me i know nothing I will mention that my very mild street clevo ran an IMPCO 425 and impco E converter which is the big boy and it was lean enough to melt the lot, off course I had to wind up the mixture which meant at idle it was burning your eyes.

S/H Twin Gas Research setup $800-$1000
New Impco 425's X2 $600 2X Impco Converters $300 you decide.

ESP · 08-19-2004, 04:13

Quote:

Originally Posted by TyreToaster

if you have the impco 425 carbs single or twin you will never get it to run the correct mixtures. Especially with you having the larger cam probably 225/236 duration 530/560ish lift you will find it either lean as buggery up high or rich as buggery down low and becuse you motor will utilise the larger rev range you may not be happy with the end result.

If you want it to run right make good power and not melt your pistons try buying s/h gas research setup much better option than the single stage adjustable IMPCO.

P.S before all you impco owners start abusing me and telling me i know nothing I will mention that my very mild street clevo ran an IMPCO 425 and impco E converter which is the big boy and it was lean enough to melt the lot, off course I had to wind up the mixture which meant at idle it was burning your eyes.

S/H Twin Gas Research setup $800-$1000
New Impco 425's X2 $600 2X Impco Converters $300 you decide.

It isn't that difficult to get a good result from the hunble IMPCO.
My Clevo runs straight gas, is making good rear wheel HP and does not run overly rich on idle. It's all about balance and building the motor for the LPG application. Long duration exhaust camshaft, right compression- higher is not always better or more efficient-correct manifold plenum vacuum and a damned good dyno operator. Remember that the motor does all the sucking as there is no pump for LPG like on petrol cars.

Admitedly, the IMPCO does lean out and mine does at 5500 RPM so I just make sure that I do not REV it past that level.

The GRA system may be better, but I have heard that they are also difficult to tune and can be expensive to muck around with.........metering rods etc.

Either way, if you build it right.............you'll be right

TyreToaster · 08-19-2004, 06:27

the research systems are hard to set by hand but any resonable dyno operator can do it right, the problem is you have the 351 your air flow rates are considerably lower.

The amount of gas/air your motor drinks at 5500rpm the 460 drinks at much lower revs.

Also I'm just guessing here becuase we dont know if he has C8/V9/D0 or D3 heads onboard its hard to say what amount of air/fuel it needs.

D3VE heads ( which are the common low performance smog based heads) are low comp in standard form but with correct piston choice his comp could be 10.5 to 1.

We know it has a stage 4 cam which in the hydraulic range genrally equates to something in the 225/235 .535/.565 range so in a 460 with stock heads we are looking at maybe 5000rpm shifts which means the impco in single form wont be enough and in dual form will be more trouble than its worth.

Sorry to all impco owners but i've pulled more motors apart with melted bits due to incorrect gas systems (incorrect for the applicsation at hand not saying the impcos are a bad thing all round) than I ever have with petrol based applications and i fix cars all day long.

TyreToaster · 08-19-2004, 06:31

oh yeah just want to mention my own car does not run GRA system and the impco 425 went in the trash can after i saw the mess it made to my motor, back on petrol for now.

ando · 08-20-2004, 22:12

i have found a bit more info on the motor which was in the car it has D3VE-A2A heads. Its has double valve springs cromoly retainers stock valves port matched, mild port .The cam has writen down as a 40-80 stage 4 i dont know if this is right though? the pistions are cast with graphite rings, Rods CJ and Rod bolts. Clevite 77 main+big end bearings.Compression is Stated as 10.5 to 1 on the paper. It sounds like the twin research is the much better way to go. Is it easy to install? I have seen it set up on a valiant before i think? Is it like bolted to a single carb manifold which splits up to type of 2 throttle bodies which sit above both heads? Do you have any pics of the setup? Or any on the net? Cheers guys thanks for the info

IMANUT · 08-21-2004, 01:01

..